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Biomedical subjects

S Omata

Publications and source records attributed to S Omata.

At least 37 records · Page 2Linked to original sources
PubMed1997

The 14-3-3 protein binds its target proteins with a common site located towards the C-terminus.

The 14-3-3 protein family binds a variety of proteins in cell-signaling pathways, but the structural elements necessary for the ligand binding are poorly understood. Here we demonstrate that the 'box-1' region, which spans residues 171-213 in the eta-isoform and was previously identified as the binding site of 14-3-3 to the phosphorylated tryptophan hydroxylase, plays a critical role in the interaction with many target proteins. Using a series of truncated 14-3-3 mutants, we show that the mutant 167-213 carrying box-1 binds bacurovirus-expressed Raf-1 and Bcr protein kinases to the similar extent as the full-length 14-3-3 in a phosphorylation-dependent manner, while the mutants lacking this region abolish the binding activity. Furthermore, the box-1 region also appears essential for binding of 14-3-3 to more than 40 phosphoproteins found in the brainstem extract. These results suggest that the box-1 region, consisting of helices 7 and 8 in the tertiary structure, is a common structural element whereby the 14-3-3 protein binds many, if not all, target proteins.

14-3-3 Proteins↗
PubMed1997

Staphylococcal enterotoxin B induces arthritis in female DBA/1 mice but fails to induce activation of type II collagen-reactive lymphocytes.

It has been proposed that superantigens are involved in the pathogenesis of autoimmune diseases. To test the possibility of superantigens inducing arthritis in naive mice, V beta 8-reactive superantigen staphylococcal enterotoxin B (SEB) was injected into naive mice. We used female DBA/1 mice, because they were susceptible to collagen-induced arthritis (CIA), in which the pathogenic T cells were supposed to preferentially use limited V betas of T cell receptors including V beta 8. Mild monoarthritis developed in uninjected hindlimbs of mice administered with SEB in higher frequency (an average incidence of 24%) than the control phosphate-buffered saline-injected mice (4.2%). Autoimmune responses in mice administered with SEB were compared with those in mice developing CIA. However, activation of type II collagen (IIC)-reactive T cells was not detected in SEB-injected mice. Production of autoantibodies, anti-IIC antibody and rheumatoid factor was also undetected. Although exact mechanisms of pathogenesis of this arthritis remain to be known, V beta 8+ T cells were activated for a long period and the unresponsiveness of V beta 8+ T cells was not detected in this strain. From these results, we discuss the pathogenesis of arthritis induced by SEB and the possibility that superantigen may play a role in the induction of autoimmune diseases.

Animals↗
PubMed1997

Comparative analysis of bladder wall compliance based on cystometry and biosensor measurements during the micturition cycle of the rat.

The stiffness characteristics of the empty and filling bladder and the modulating influence of oxybutynin were investigated using a new biosensor system. Studies were done comparing the stiffness measured using the pressure/volume relationship with direct biosensor monitoring on male and female rats during isovolumetric contractions elicited during the cystometrogram (CMG). Bladder stiffness at zero volume, measured in vitro using the biosensor, was evaluated and compared with the stiffness of the prostate, seminal vesicles, testicles, and uterus. In 5 small anesthetized male rats, in vivo isovolumetric studies were performed and bladder stiffness was measured during the storage and contraction phase of the CMG. In 6 mature female rats, change in bladder stiffness during isovolumetric contractions was investigated following intraarterial (i.a.) administration of 0.1 and 1.0 mg/kg of oxybutynin. After the in vivo CMG was completed, an in vitro CMG was done measuring bladder stiffness. The results show that bladder stiffness, measured during the storage phase of the CMG, increased in accordance with the stretched length of bladder wall. During the in vivo CMG, bladder stiffness increased consequent to a spontaneous contraction from 10.0 +/- 1.9 g/cm to 29.9 +/- 3.0 g/cm (P < 0.005). Oxybutynin produced a significant decrease in bladder stiffness during the storage phase of the CMG, as measured using the biosensor, which was concomitant with an increase in bladder compliance derived from pressure/volume data. The incremental change in stiffness, delta K, during isovolumetric contraction decreased due to i.a. oxybutynin in accordance with a decrease of maximum detrusor pressure. These results indicate that delta K is related to the active change of viscoelastic properties of bladder smooth muscle. These findings imply that direct measurement of the stiffness of the bladder wall possesses the potential to be an objective assessment of bladder biomechanical properties and of their functional response to obstruction and pharmacological intervention.

Animals↗
PubMed1997

cDNA cloning of nuclear localization signal binding protein NBP60, a rat homologue of lamin B receptor, and identification of binding sites of human lamin B receptor for nuclear localization signals and chromatin.

We previously purified and characterized a nuclear localization signal (NLS) binding protein, NBP60, in rat liver nuclear envelopes. In this study, we cloned and sequenced the cDNA of rat NBP60, and predicted an amino acid sequence comprising 620 amino acids. The sequence revealed that NBP60 is a rat homologue of lamin B receptor (LBR), and is 79 and 63% identical in amino acids to human and chicken LBR, respectively. Using three fusion proteins containing different parts of the amino-terminal domain of human LBR, it was shown that the stretch comprising amino acids 1 to 89, which contains a Ser-Arg rich region (RS region), binds to nucleoplasmin and that the binding was inhibited by a common NLS-peptide. These results suggested that the amino-terminal domain of LBR contains an NLS-binding site. Furthermore, it was shown that the stretch comprising amino acids 1 to 53, which does not contain the RS region or the predicted DNA-binding site, binds to Xenopus laevis sperm chromatin.

Amino Acid Sequence↗
PubMed1997

Characterization of the binding of nuclear envelope precursor vesicles and chromatin, and purification of the vesicles.

The binding of nuclear envelope precursor vesicles and chromatin was characterized by using an in vitro system constituted from a Xenopus egg extract and demembranated Xenopus sperm chromatin. The results of binding studies in the presence of salts, urea, and a chelator showed that the binding involves an ionic interaction. Chemical modification studies suggested that a protein(s) in the vesicles, which is responsible for the binding with chromatin, has essential lysine, histidine, and methionine residues. The vesicle protein could not be extracted from vesicles with 1 M KCl, 2 M urea, or 0.1 M Na2CO3, suggesting that it is an intrinsic membrane protein. The protein was denatured with 8 M urea and 0.1 M Na2CO3, and could be renatured by incubation at 23 degrees C, suggesting that the native conformation of the protein is important for the binding. Affinity purification of nuclear envelope precursor vesicles was achieved by binding to chromatin and dissociation with 0.24 M NaCl. The vesicle fraction thus obtained exhibited the ability to form nuclear envelope on incubation with chromatin in Xenopus egg cytosol without any other membrane fraction. These results suggested that there is a nuclear envelope precursor vesicle population containing both a chromatin targeting protein and vesicle fusion machinery.

Animals↗
PubMed1997

The effects of substituents introduced into 9-aminoacridine on frameshift mutagenicity and DNA binding affinity.

Some derivatives of 9-aminoacridine (1) were synthesized, and their frameshift mutagenicity and DNA binding affinity were studied. The introduction of a methyl group into the acridine ring of 1 reduced the mutagenic activity and the intercalative DNA binding affinity, while the introduction of chlorine increased them. Halogenated derivatives of 1 showed higher toxicity against Salmonella typhimurium TA1537.

Aminacrine↗
PubMed1997

Regional myocardial stiffness measured by a new tactile sensor system.

Numerous investigators have attempted to measure regional wall stress directly. However, the measurement systems and devices employed have been too complex for accurate quantification in situ. We have developed a new tactile sensor system for measuring accurately myocardial stiffness in situ and validated its use for estimation of myocardial contractile function. The tactile sensor was placed on the left ventricle of five mongrel dogs, (weighing 12-17 kg) and myocardial stiffness (g/mm2) was measured. Dobutamine (5.0 micrograms/kg/min) and propranolol (0.25 mg/kg) were sequentially administrated intravenously, and the change in myocardial stiffness was monitored. Myocardial stiffness followed a time course similar to that of left ventricular pressure, indicating a close relationship with wall stress. Baseline end-systolic stiffness in 5 dogs was 2.38 +/- 0.19 g/mm2. After administration of dobutamine, end-systolic stiffness increased to 3.26 +/- 0.32 g/mm2 (p < 0.01). After the administration of propranolol, end-systolic stiffness decreased significantly to 1.83 +/- 0.19 g/mm2 (p < 0.01), compared with the baseline values. Regional myocardial stiffness of a beating heart can be measured precisely using our new tactile sensor system. End-systolic stiffness is a useful index for accurate quantification of the regional myocardial contractile state.

Animals↗
PubMed1997

Tactile sensor method for thoracoscopic detection of intrapulmonary nodules.

We have developed a tactile sensor which can be used to quantify the hardness of objects and applied it to thoracoscopic surgery for the localization of small invisible nodules in the lung. The hardness properties of objects can be obtained as changes in the resonance frequency of the tactile sensor (delta f). When the sensor probe is moved over the lung surface, a delta f curve is depicted on the computer screen. When the sensor tip passes the area just above a target nodule, a spike is evoked in the delta f curve. In thoracoscopic surgery, tactile sensor was employed to detect a total or 42 nodules, 32 indeterminate and 10 metastatic, in 37 patients. All except two of these detected nodules, had been preoperatively demonstrated with computed tomography. Each nodule was detected successfully by recognizing the spot on the pleura, at which the spike of delta f curve was evoked, and resected thoracoscopically. All of the indeterminate nodules were diagnosed intraoperatively; 28 benign tumors and 4 primary carcinomas. In conclusion, our tactile sensor method can be a viable alternative for thoracoscopic detection of small and invisible pulmonary nodules.

Humans↗
PubMed1996

Subcellular distribution and phosphorylation of the nuclear localization signal binding protein, NBP60.

We previously purified a nuclear localization signal binding protein, NBP60, from rat liver (1993, J. Biochem. 113, 308-313). In this study, the subcellular localization of NBP60 was examined using anti-NBP60. Most NBP60 was found to be localized in the nuclear envelope fraction of rat liver obtained on cell fractionation followed by immunoblotting. Staining of the nuclei of cultured cells by the antibody was observed on immunofluorescence microscopy. NBP60 was widely detected in rat nuclear fractions prepared from other tissues and also in nuclei of cultured cells derived from other species. It was shown by immunoelectron microscopy that most NBP60 is present in the nuclear envelope and at least some of that is present on nuclear pore complexes. Although NBP60 was localized in the nuclear envelope in interphase cells, it diffused into the cytoplasm in the mitotic phase. The purified NBP60 was highly phosphorylated by a cdc2 mitotic kinase, whereas nuclear pore proteins p144, p62, p60, and p54 were not phosphorylated by the kinase directly. NBP60 was also phosphorylated by protein kinase A, calmodulin-dependent protein kinase II, and casein kinase II. The phosphorylation of NBP60 by cdc2 kinase and/or the other kinases may be related to the change in the protein's location during the mitotic phase.

Animals↗
PubMed1996

Analysis of the relative biomechanical effects of alpha 1 and alpha 2 antagonists in modifying the compliance of the prostate and micturition parameters of the hormonally manipulated male rat.

The potential of the alpha 1 and alpha 2 antagonists to modify prostate compliance, and micturition characteristics of rats with hormonally enlarged prostates was studied. Prostate growth was induced in Sprague-Dawley rats using dihydrotestosterone (DHT) and estradiol (E) by daily subcutaneous injections of DHT 1.25 mg/kg and E 0.25 mg/kg together with 0.1ml of sesame oil, as a vehicle, for a period of 3 weeks. A control group of six rats was used wherein the vehicle alone was administered. Dose levels of 3, 10, 30, and 300 micrograms/kg of alpha 1 or alpha 2 antagonist were given at weekly intervals to each of the groups defined above. Voiding characteristics, in terms of micturition frequency and volume per micturition, were measured and correlated with the pharmacological and hormonal stimulus. Prostate compliance and weight was evaluated in each of the groups after rats were terminated and the ventral prostate was dissected and removed in in toto. Compliance measurements were made using a new biosensor system which is based on the principle of detecting the shift in the resonance frequency of the biosensor produced by the hormones on the acoustic impedance of prostate. The results show that DHT and [DHT+E] significantly increased prostate weight and decreased prostate compliance. The alpha 2 antagonist atipamezole significantly increased the compliance of all prostates, including controls, while the alpha 1 antagonist did not alter the compliance. It is concluded that this alpha 2 antagonist is more effective than the prazosin in reversing the hardening effect of hormones on the prostate.

Adrenergic alpha-Antagonists↗
PubMed1996

Usefulness of a new tactile sensor for measurement of uterine cervical ripening in mice in a quantitative and noninvasive manner.

OBJECTIVE: The purpose of this study was to establish a method with a new tactile sensor for determining in a quantitative and noninvasive manner the extent of uterine cervical ripening. STUDY DESIGN: We used a newly designed tactile sensor to measure the softness of the cervix in untreated nonpregnant, pregnant, parturient, and nursing mice and then on day 15 of gestation in pregnant mice treated with dehydroepiandrosterone sulfate or Escherichia coli lipopolysaccharide. Additionally, to elucidate the correlation between the extent of cervical softness and its morphologic changes, we observed microscopically the uterine cervices. RESULTS: The hardness of the murine cervix decreased with the progression of pregnancy and became minimal at delivery. We demonstrated for the first time with a tactile sensor for measuring hardness that dehydroepiandrosterone sulfate and lipopolysaccharide significantly decreased the stiffness of the murine cervix. These findings were supported by the morphologic observations on the cervices. CONCLUSIONS: These results show that the tactile sensor for measuring hardness makes it possible to determine the extent of cervical ripening quantitatively rather than qualitatively. We consider that cervical ripening determined objectively in this manner is a good parameter to predict the onset of preterm delivery.

Animals↗
PubMed1996

Characterization of p92, karyopherin beta, co-purified with N-acetylglucosamine-bearing nucleoporins from rat liver nuclear envelopes.

A 92k protein (p92) was purified from the wheat germ agglutinin-Sepharose (WGA-Sepharose) bound fraction of a rat liver nuclear envelope salt-extract by DEAE-5PW and hydroxyapatite HPLCs. Partial amino acid sequence analysis of p92 revealed that it is karyopherin beta, which was found recently in the cytosolic fraction. It was shown using anti-p92 antiserum that the protein is present in the nuclear envelope and cytosolic fractions, in almost the same amounts, but not in other subcellular fractions of rat liver. p92 bound to N-acetylglucosamine bearing nucleoporins (GNPs) on WGA-Sepharose, but not directly to WGA. The amount of p92 found in the rat liver nuclear envelope fraction corresponded to about 10% of the nuclear pore complex in mass, and to as much as 140 mol of p92 per mol of nuclear pore complex. Hydrodynamic analysis of the purified p92 suggested that the molecule is present as a monomer and that it is a rod-shaped molecule. The interaction of p92 and GNPs seemed to be hydrophobic and ionic. Based on these results, the participation of nuclear envelope p92 in protein nuclear transport is discussed.

Acetylglucosamine↗
PubMed1996

Clinical applicability of a new tactile sensor for evaluating rigidity of the penis: a comparative study with Rigiscan.

BACKGROUND: A new tactile sensor was developed for detecting hardness of living tissue by Omata et al. in 1992. This paper reports applicability of the sensor for evaluation of penile rigidity. METHODS: Nine patients from a group of 12 patients with penile erectile dysfunction were selected as subjects of this study. All patients agreed to artificial erection and monitoring of penile rigidity by a new tactile sensor and the Rigiscan system. The 9 patients selected all developed more than 1 cm circumferential expansion of the penis after an injection of smooth muscle relaxant into the corpus cavernosum. The sensor equipment consisted of a piezoelectric element that vibrated, and a pickup that detected vibration frequency. When the end of the sensor was pressed against a surface of the penis, the resonance frequency of the sensor changed and indicated rigidity of the organ. Rigidity of the penile shaft was simultaneously monitored with the sensor and the Rigiscan system before and after an injection of 40 mg papaverine or 20 micrograms prostaglandin E1. The sensor's measurements of rigidity were compared with those of Rigiscan. RESULTS: Reproducibility of rigidity measured with the tactile sensor was satisfactory. Statistical analysis was made on 85 simultaneous pairs of rigidity values from the tactile sensor and Rigiscan. The analysis indicated significant correlation between the values. CONCLUSION: The tactile sensor as well as Rigiscan will be of use for evaluating rigidity of the penis.

Adult↗
PubMed1995

Identification of the site of interaction of the 14-3-3 protein with phosphorylated tryptophan hydroxylase.

The 14-3-3 protein family plays a role in a wide variety of cell signaling processes including monoamine synthesis, exocytosis, and cell cycle regulation, but the structural requirements for the activity of this protein family are not known. We have previously shown that the 14-3-3 protein binds with and activates phosphorylated tryptophan hydroxylase (TPH, the rate-limiting enzyme in the biosynthesis of neurotransmitter serotonin) and proposed that this activity might be mediated through the COOH-terminal acidic region of the 14-3-3 molecules. In this report we demonstrate, using a series of truncation mutants of the 14-3-3 eta isoform expressed in Escherichia coli, that the COOH-terminal region, especially restricted in amino acids 171-213, binds indeed with the phosphorylated TPH. This restricted region, which we termed 14-3-3 box I, is one of the structural regions whose sequence is highly conserved beyond species, allowing that the plant 14-3-3 isoform (GF14) could also activate rat brain TPH. The 14-3-3 box I is the first functional region whose activity has directly been defined in the 14-3-3 sequence and may represent a common structural element whereby 14-3-3 interacts with other target proteins such as Raf-1 kinase. The result is consistent with the recently published crystal structure of this protein family, which suggests the importance of the negatively charged groove-like structure in the ligand binding.

14-3-3 Proteins↗
PubMed1995

Separation of membrane proteins solubilized with a nondenaturing detergent and a high salt concentration by hydroxyapatite high-performance liquid chromatography.

Ceramic hydroxyapatite high-performance liquid chromatography with a solvent containing high concentrations of salts was used for the separation of membrane proteins solubilized under nondenaturing and high salt conditions. The chromatographic conditions were optimized using sodium cholate as the detergent. By this method, most membrane proteins, prepared from rat liver rough microsomes, were effectively resolved from each other with a protein recovery of more than 90%. The method also allowed the single-step purification of the ribosome-binding protein, p34, from a microsomal membrane protein fraction. The good resolution with this method should be applicable to the isolation and characterization of a variety of membrane proteins on the analytical and semipreparative scales. With only the substitution of sodium cholate with other nondenaturing detergents, this method may also be applicable to the purification of membrane proteins requiring such nondenaturing detergents with retention of their biological activities.

Cholic Acid↗
PubMed1995

Impression technique for the assessment of oedema: comparison with a new tactile sensor that measures physical properties of tissue.

To measure tissue oedema, the impression technique and a new tactile sensor technique are compared and evaluated in a silicone rubber model and in an in vivo rat testis model. The principles of the two techniques differ in that the impression technique evaluates interstitial fluid flow FT and peak force F(O) when tissue is compressed, whereas the tactile sensor evaluates the hardness/softness or change in resonance frequency delta f when a vibrating rod is attached to tissue. Both techniques can detect changes in silicone hardness/softness or in hormone-induced changes of testis interstitial fluid. Although both F(O) and FT are significantly correlated to delta f in the experiments, it is concluded that F(O) is the most promising impression parameter to give valuable information about the hardness of living tissue as compared with delta f. The comparison indicates that the impression technique is the most easy to interpret, non-invasive tool to assess tissue oedema so far developed.

Animals↗
PubMed1995

Application of a new tactile sensor to thoracoscopic surgery: experimental and clinical study.

BACKGROUND: We developed a new tactile sensor that could quantify the hardness of objects as changes in the resonance frequency of the sensor (delta f). We have applied it to thoracoscopic operations for the localization of small invisible nodules in the lung. METHODS: When the sensor probe was moved over the lung surface, a delta f curve was depicted on the computer screen. When the sensor tip reached a point directly above a hard object, a sudden upward jump of the delta f curve was evoked. After experimental studies using pigs, the sensor was applied in 8 patients. More recently we produced a needle sensor to distinguish small nodules from bronchi that may evoke similar upward jumps of the delta f curve. Eight nodules and four bronchi in resected human lungs were probed directly using this sensor. RESULTS: In all of the patients, the hardness of various thoracic structures could be quantified. A total of 10 nodules were found using the sensor and resected thoracoscopically. The needle sensor distinguished nodules from bronchi, as the mean delta f of the bronchial walls (-64 +/- 45.9 Hz) was significantly higher than that of nodules (-526 +/- 168 Hz, p < 0.001). CONCLUSIONS: Thoracoscopic detection of small and invisible pulmonary nodules using our new tactile sensor is feasible.

Adenocarcinoma↗